How to make a material switching from Wire frame material to surface material?
I don't know if there is a better way (I don't usually use Blender Internal) but this can be done with material nodes to generate the wireframe using the UV coordinates.

To generate the wireframe we can use the default unwrap (or use UV Unwrap->Reset to reset back to default) and have the material solid if U or V is less than 0.1 or greater than 0.9 (use values closer to 0.0/1.0 for thinner lines).

To get the wireframe to slide across the mesh we can split the coordinates into the respective components and use Math nodes to generate a cutoff, keyframing the value to animate the transition. Note that I've used the X coordinate (split from the vector using the Separate RGB node (RGB translates to XYZ), combined with a fraction of Z so as to make the transition plane not coincide with the sides of the cube (or you get an ugly transition as the whole face jumps between being transparent and not transparent).



Ensure to enable Transparency in the Render Pipeline Options of the material to allow transparent materials.

This produces the following result :